FOSTRAD : An advanced open source tool for re-entry analysis

This work responds to the need of modeling the atmospheric re-entry of space debris, satellites, and spacecraft quickly, efficiently and with a reasonable reliability. The Free Open Source Tool for Re-entry of Asteroids and Debris (FOSTRAD) is a simulation suite that allows for the estimation of aerodynamics and aerothermodynamics of an entry object in a continuum or rarefied hypersonic flow by employing the local panel formulation. In this paper, the work done to integrate the tool within a comprehensive framework allowing the simulation of complex geometries using a mesh handler module, a 3DOF trajectory propagator, and a surrogate model generation function, is presented. In addition, a synchronous coupling with a 1D thermal ablation code has been implemented and tested. The mesh module allows operations such as surface local radius computation, surface facets visibility identification, and objects geometrical evolution due to the burn-up during the re-entry. In the continuum regime, the simplified aerothermodynamics are computed using a local radius formulation, while the tool employs a flat-plate based approach in the free molecular regime. A generalized nose radius-based bridging model has been introduced for the rarefied transitional regime. The tests have demonstrated that applying a local radius formulation along with the radius-based bridging model greatly improves the accuracy of re-entry heat-flux estimations. The integrated framework has been tested on two different examples of atmospheric re-entries: the ESA Intermediate Experimental Vehicle (IXV) trajectory optimization and the Stardust sample return capsule Thermal Protection System (TPS) burn-up recession; and the coupling between FOSTRAD and the thermal ablation code allowed to study a step-by-step trajectory evolution of Stardust TPS. The obtained results show good agreement with the literature

DMTMM, un nuovo reattivo di "coupling" per la sintesi di ammidi in fase solida ed in fase omogenea

La formazione di un legame ammidico é la reazione per la quale esistono forse più metodi disponibili in letteratura. Nonostante tale abbondanza di metodi, non sono molti i reattivi che formano un legame ammidico direttamente a partire dall’acido carbossilico e dalla ammina, che funzionano sia su fase solida che su fase omogenea senza la formazione di molti sottoprodoti e che limitano la possibilità di racemizzazione allorquando si lavori con α-amminoacidi. Molto versatile é risultato il sale di N-metil morfolinio della 4,6-dimetossi[1,3,5]triazina (DMTMM), ottenuto direttamente dalla 2-cloro, 4, 6-dimetossi[1,3,5]triazina per reazione con Nmetil morfolina, che é un solido isolabile e stabile

Aero-thermal re-entry sensitivity analysis using DSMC and a high dimensional model representation-based approach

This paper presents a sensitivity analysis for the hypersonic aero-thermal convective heat transfer from the free molecular to the slip-flow regime for cylindrical and cubic geometries. The analyses focus on a surface-averaged heat transfer coefficient at various atmospheric conditions. The sensitivity analyses have been performed by coupling a High Dimensional Model Representation based approach and a Direct Simulation Monte Carlo code. The geometries have been tested with respect to different inputs parameters; altitude, attitude, wall temperature and geometric characteristics. After the initial sensitivity analyses, the N-dimensional surrogate models of the surface-averaged heat transfer coefficient have been defined and tested. Hereby, a shape-based DSMC mesh refinement correction factor for reducing the overall analyses computational times is also presented

Sviluppo di "spot tests" visivi per la determinazione della presenza di gruppi funzionali in sintesi organica supportata su fase solida

Nei nostri laboratori abbiamo messo a punto due "spot tests" visivi molto efficienti per la determinazione di gruppi -COOH e per gruppi -OH di tipo alcolico o fenolico

Launcher vehicle aerothermodynamics and fairing separation altitude effects on payload temperature

The first part of this research investigates and compares VEGA launcher vehicle aerothermodynamics during a nominal ascent trajectory simulated by means of Direct Simulation Monte Carlo and hypersonic local panel methods. In the second part of the work, the coupled aerothermal-structural simulation of the ascent phase up to 250s was performed, studying the heat transfer between the payload fairing and a dummy payload. The results have shown a good match among the aerothermal fluxes estimated by the different methodologies, and that an optimal theoretical fairing separation time can be found by minimizing the aerothermal fluxes incident on the payload

Detecting Images Generated by Diffusers

This paper explores the task of detecting images generated by text-to-image diffusion models. To evaluate this, we consider images generated from captions in the MSCOCO and Wikimedia datasets using two state-of-the-art models: Stable Diffusion and GLIDE. Our experiments show that it is possible to detect the generated images using simple Multi-Layer Perceptrons (MLPs), starting from features extracted by CLIP, or traditional Convolutional Neural Networks (CNNs). We also observe that models trained on images generated by Stable Diffusion can detect images generated by GLIDE relatively well, however, the reverse is not true. Lastly, we find that incorporating the associated textual information with the images rarely leads to significant improvement in detection results but that the type of subject depicted in the image can have a significant impact on performance. This work provides insights into the feasibility of detecting generated images, and has implications for security and privacy concerns in real-world applications. The code to reproduce our results is available at: https://github.com/davide-coccomini/Detecting-Images-Generated-by-Diffuser

Multi-hormonal analysis and aquaporins regulation reveal new insights on drought tolerance in grapevine

Disentangling the factors that foster the tolerance to water stress in plants could provide great benefits to crop productions. In a two-year experiment, two new PIWI (fungus resistant) grapevine varieties, namely Merlot Kanthus and Sauvignon Kretos (Vitis hybrids), grown in the field, were subjected to two different water regimes: weekly irrigated (IR) or not irrigated (NIR) for two months during the summer. The two varieties exhibited large differences in terms of performance under water-limiting conditions. In particular, Merlot Kanthus strongly decreased stem water potential (Ψs) under water shortage and Sauvignon Kretos maintained higher Ψs values accompanied by generally high stomatal conductance and net carbon assimilation, regardless of the treatment. We hypothesized differences in the hormonal profile that mediate most of the plant responses to stresses or in the regulation of the aquaporins that control the water transport in the leaves. In general, substantial differences were found in the abundance of different hormonal classes, with Merlot Kanthus reporting higher concentrations of cytokinins while Sauvignon Kretos higher concentrations of auxins, jasmonate and salicylic acid. Interestingly, under water stress conditions ABA modulation appeared similar between the two cultivars, while other hormones were differently modulated between the two varieties. Regarding the expression of aquaporin encoding genes, Merlot Kanthus showed a significant downregulation of VvPIP2;1 and VvTIP2;1 in leaves exposed to water stress. Both genes have probably a role in influencing leaf conductance, and VvTIP2;1 has been correlated with stomatal conductance values. This evidence suggests that the two PIWI varieties are characterized by different behaviour in response to drought. Furthermore, the findings of the study may be generalized, suggesting the involvement of a complex hormonal cross-talk and aquaporins in effectively influencing plant performance under water shortage

Alveolar ridge split technique using piezosurgery with specially designed tips

The treatment of patients with atrophic ridge who need prosthetic rehabilitation is a common problem in oral and maxillofacial surgery. Among the various techniques introduced for the expansion of alveolar ridges with a horizontal bone deficit is the alveolar ridge split technique. The aim of this article is to give a description of some new tips that have been specifically designed for the treatment of atrophic ridges with transversal bone deficit. A two-step piezosurgical split technique is also described, based on specific osteotomies of the vestibular cortex and the use of a mandibular ramus graft as interpositional graft. A total of 15 patients were treated with the proposed new tips by our department. All the expanded areas were successful in providing an adequate width and height to insert implants according to the prosthetic plan and the proposed tips allowed obtaining the most from the alveolar ridge split technique and piezosurgery. These tips have made alveolar ridge split technique simple, safe, and effective for the treatment of horizontal and vertical bone defects. Furthermore the proposed piezosurgical split technique allows obtaining horizontal and vertical bone augmentation